1. Field of the Invention
This invention relates to the field of fluid transport, and more particularly to methods and apparatus for joining two pieces of fluid drip tape.
2. Description of Prior Art
It is often necessary to join two pieces of drip tape. For example, it may be desired to repair a tape which has begun to leak or more simply just to extend a line of tape. This operation is typically accomplished by cutting the tape into two sections and then cutting away a small length of the tape section containing the leak. Then the two sound sections of tape are spliced together to create a final, leak-tight longer section. The splice is often accomplished by inserting, within one section of the tape, a barbed coupling consisting of an essentially cylindrical structure having several circumferential ridges--i.e., frustoconical barbs--along its length. The frustoconical barb diameter is normally slightly larger than the inner diameter of the tape, to insure a close fit. A wire tie or tightening sleeve (such as a conventional screw-driven hose clamp, as used to connect a radiator hose to a radiator) is then slid over that section of tape, so that it surrounds a portion of the coupling within the tape. Another wire tie or tightening sleeve is slid over the opposing section of tape. Then that opposing section of tape is slid over the other end of the barbed coupling. Finally, both wire ties are tightly twisted, or the tightening sleeves are screw-tightened, so that the two tape sections are respectively sealed against the coupling within them. The result is a leak-tight tape.
In an exactly similar manner, two tapes may be joined by insertion of such a coupling. When each section is sealed to the coupling, by means of a wire tie or tightening sleeve, a longer tape is created with a fluid-tight junction. Similarly, this could be done to produce longer sections of plastic tape for irrigation use.
Such splicing of fluid drip tape sections has particular application in the field of crop irrigation. The days of unlimited water for irrigation are long since past. Today, it is necessary to conserve irrigation water, and this is commonly accomplished by use of drip tapes. A drip tape is essentially a thin walled, flexible water drip tape. It is normally flat in cross-section until water is driven through it, whereupon it swells to an essentially elliptic or even circular cross-section. Along the length of a drip tape are a succession of drip holes, through which a reasonably determinable flow of water is allowed to pass when the drip tape is in use. When the drip tape is installed, these holes are placed at those locations where it is desired to deliver water, for example at planted seeds or the roots of plants. The entire tape, or portions of it, may be buried beneath the surface, so as to reduce loss by evaporation and to insure delivery of water near the exact location desired, without wastage by moistening unproductive soil.
In actual use, these drip tapes are joined in a complex network of channels, fed by a single inlet source of water. Thus, merely by opening a valve at the inlet, water may be supplied, drip by drip, to those particular locations--perhaps many thousands in number--where pinpoint irrigation is desired. Of course, in order to create such a network, a large number of drip tapes must be joined.
Typically, these splices have been accomplished in a manner closely analogous to the tape splicing method discussed above. Each piece of drip tape is slipped over an coupling--usually made of plastic--from opposite ends, and each end is water-sealed to the coupling by means of a wire tie. One tie is used for each end of the drip tape.
However, this commonly-employed method is wasteful, largely because application of two wire ties to a single splice requires a considerable amount of time. Because of increasing agricultural labor rates, this expenditure of time can accumulate alarmingly. Also, it is clear that use of two wire ties or tightening sleeves per junction entails purchase of a vast number of such sealing elements. Either or both of these costs--for labor and hardware--can add greatly to the cost of food production, which, particularly from the farmer's point of view, is generally a low-margin business.
What is needed is a method of joining two pieces of thin walled drip tapes, which does not require two separate wire ties or tightening sleeves. Clearly, this can not readily be accomplished simply by inserting the end of one piece of drip tape over one end of the coupling, then sliding the end of the other drip tape over the first to overlap it and finally sealing the junction by applying a single wire tie or tightening sleeve to the overlap portion. While this might theoretically be possible with drip tapes, which are thin and flexible, even here it would be difficult to slide the end of one drip tape over the other sufficiently to create a water-tight seal--at least without the expenditure of at least as much effort as would be required to apply a second wire tie or tightening sleeve.
Thus, what is needed is some type of splicing coupling which is economical to manufacture, whose use is simple and requires only a single wire tie or tightening sleeve per junction.